1. Field of the Invention
The present invention relates to an identification method for cross directional position correspondence in equipment that manufactures sheet form products, in which the position correspondence between actuators for controlling cross direction profiles of the sheet and measuring points for these profiles can be automatically identified, and to manufacturing equipment using this method for sheet form products.
2. Description of the Prior Art
FIG. 1 shows a configuration of a portion to control cross direction profiles in the equipment for manufacturing sheet form products such as paper. Hereafter description will be made pertaining to paper manufacturing equipment. In FIG. 1, the raw material pulp is made into sheet form by being sent out to wire part 42 from the gap of slice lip 41. The width of the gap of slice lip 41 is adjusted by slice bolts 43. Moisture contained in the pulp which has been made into sheet form is removed during the time interval in which the pulp is carried in the direction of arrow 44 on wire part 42, and a profile of the thickness of the pulp is measured at BM frame 45.
Since the measuring interval at BM frame 45 is about 5 mm while distances between slice bolts 43 are 35 to 100 mm, two or more measuring points correspond to one slice bolt. Which measuring points correspond to which slice bolt cannot be determined with their geometrical relations only. For this reason, tuning for these position correspondences is carried out at machine start-up.
FIG. 2 shows the tuning flow for position correspondence. First, an automatic step response test is carried out, in which a step manipulated variable is given to the actuators (slice bolts 43) and a change in the cross direction profile corresponding to this manipulated variable is measured. This is performed, for example, using the technique mentioned in Japanese Laid-open Patent Application No. 9-316791.
Next, positions of measuring points corresponding to each actuator are individually determined by analyzing the results of this step response test. This method of determination is carried out, for example, using the technique mentioned in Japanese Laid-open Patent Application No. 9-049185. Finally total position correspondence, which settles position correspondences for all actuators, is determined by smoothly interpolating these individual position correspondences. This is carried out, for example, using a procedure mentioned in Japanese Laid-open Patent Application No. 9-132892.
During implementation of the automatic step response test, it is difficult to maintain good profiles because the number of manipulating bolts of the actuators and manipulated variables of the actuators are limited and thus it is difficult to implement the test during machine operation in view of quality control. Accordingly, the usual procedure is that position correspondence between the actuators and the measuring points is determined based on the flow shown in FIG. 2 at control start-up and this position correspondence is used in a fixed manner during machine operations.
However, determination of position correspondence between the actuators and the measuring points by such a method has the following problems:
When an automatic step response test is being implemented, tuning operators must continue to monitor the test. However, at times when there are many actuators, there can be from 100 to 200 of them. This results in the problem of a very great load being imposed on the tuning operators.
In addition, if a recipe for the sheet raw material changes, position correspondence also changes. For this reason, the usual procedure is that individual position correspondences are stored for each recipe and if a recipe is changed, the stored position correspondence is called up and re-set. However, there is also the problem that the position correspondence must be identified by implementing an automatic step response test for each recipe and considerable man hours become necessary for tuning work.
Further, if the machine operating conditions such as basis weight and machine speed or other production conditions change, position correspondence changes even if the raw material recipe remains the same, and the above determination method cannot cope with such cases. Thus there is also another problem with the above method in that controllability deteriorates resulting in the production of defective products.
Consequently, the objective of the present invention is to offer an identification method for cross directional position correspondence that can automatically determine and re-set position correspondence between the actuators and the measuring points during machine operation, and to provide manufacturing equipment using this method for sheet form products.